The present invention relates to a process for forming a highly impervious, water-resistant, pin hole free, essentially hermetic coating. More particularly, the present invention relates to a process for forming a coating of a novel hydrolyzed polymeric ethylene vinyl ester.
While the coating art is very old and offers a panoply of coating techniques, processes, coating compositions and resins, the number of processes and compositions capable of yielding a truly impervious and non-porous layer are few. In many cases due simply to the nature of the materials themselves and the application techniques that are used, these hermetic qualities are unavailable and it is not possible to completely seal the substrate coated from its environment. In particular, many coating techniques that apply a solvent based composition and evaporate the solvent to dryness in the process produce a coating having a microporous network through which air and moisture may contact the underlying surface and cause corrosion. Thus, even if the substrate is coated on all sides it is not completely protected from air and moisture.
Frequently, coatings also do not provide adequate adherence to the underlying surface. This not only can lead to the problem of peeling but can also detract from hermetic qualities. For example, where the coating suffers some localized damage, if it is not adherent, air and water may penetrate between the coating and the surface and render the coating ineffective even in the undamaged areas.
Thus, there is always a need for processes which yield impervious, pin hole free encapsulating coatings. Another need is for an impervious coating which adheres strongly to the coated substrate.